Processes for the ortho-alkylation of phenolic compounds with an alcohol are known in the art. Typically, the reaction is carried out in the vapor phase using a metal-containing catalyst, for example, those based on magnesium alone or both magnesium and manganese. Various catalysts and methods for their preparation are described in the patent literature. For instance, magnesium oxide alone is useful as such a catalyst (Van Sorge, U.S. Pat. No. 3,972,828). Also suitable are finely divided mixtures of magnesium and manganese oxides (Van Sorge, U.S. Pat. Nos. 3,972,836 and 3,974,229). Mixtures of magnesium oxide and manganese sulfate are useful as well (Van Sorge, U.S. Pat. No. 3,873,628). These patents mention that the magnesium oxides may be derived by the thermal decomposition of magnesium carbonate.
Magnesium oxide as an ortho-alkylation catalyst is also disclosed in U.S. Pat. Nos. 3,446,856 and 3,479,410 (Hamilton).
More recent developments have involved the use of procedures in which catalyst precursors are first prepared by precipitating manganese hydroxide from a solution of a soluble manganese salt, onto magnesium carbonate or magnesium hydroxide, then activating the precursors by calcining it at elevated temperatures sufficient to form oxides. The resulting catalyst is uniform and provides good yields and good selectivity to the end product.